1. Technical Field
The present disclosure relates to a printed circuit board (PCB).
2. Description of Related Art
Differential pairs are often used in a multi-layer PCB to transmit signals. A PCB usually has an edge-coupled differential pair in which two transmission wires are defined in the same signal layer and are coupled with each other. The PCB may also have a broadside-coupled differential pair in which two transmission wires are defined in two different signal layers and are coupled with each other. If an edge-coupled differential pair and a broadside-coupled differential pair are simultaneously used in a multi-layer PCB, each transmission wire will have a coupled portion and an uncoupled portion. A vertical via which stands for “vertical interconnect access” is used in vertical electrical connection between different layers in PCB design. However, the uncoupled portion may cause inconsistent impedance of the differential pairs. As a result, the signal transmission is influenced.
Therefore, it is desirable to provide a printed circuit board, which can overcome or at least alleviate the limitations described.